A host of celebrities have written an open letter to David Cameron calling on Britain to do more to help Syria's refugees find safety in the UK.

Oscar winner Emma Thompson, comedian Michael Palin and musician Sting are among those who told the Prime Minister they were "ashamed" by Britain's efforts so far.

The Syrian vulnerable persons relocation scheme was set up at the start of last year after the Government was pressured into dropping its previous opposition to admitting refugees directly from the region.

Ministers argued that the UK, as the second biggest contributor to aid funds for the war-torn country, could contribute more by improving conditions on the ground.

The scheme expects to relocate only a few hundred Syrians over the next three years.

Downton Abbey's Michelle Dockery, fashion designer Dame Vivienne Westwood and director Ken Loach also signed the letter to Mr Cameron, which was in support of a joint campaign by the Refugee Council, Amnesty International and Oxfam.

They told the Prime Minister: " In a climate where children are sent to work in order to help their parents survive, where young girls are sold off as child brides and where torture victims are unable to rebuild their lives, every resettlement place countries like Britain provide is a lifeline.

"Resettling 'several hundred people' just isn't good enough for a global leader. This issue isn't about migration statistics or party politics, it's about people. It's about the values that we in Britain hold dear; compassion and humanity.

"Your choice is simple, yet historic. You are in a position to offer some of the most vulnerable people in the world safety in Britain. You can offer hope. You can offer a future."

The letter also described how countries such as Germany and Austria have increased the number of places they are offering in light of the deteriorating situation in the Middle East with the rise of Islamic State.

"We are ashamed that the UK has so far failed to do likewise," the celebrities added.

The UN's Refugee Agency UNHCR is calling on governments around the world to offer 100,000 resettlement places for Syria's refugees in 2015/2016.

Refugee Council chief executive Maurice Wren said: "The Syrian crisis presents us with one of the greatest refugee crises of our time and, arguably, one of the greatest moral questions of our time.

"The UK's commitment to the relief effort has been laudable but it's not enough. The question is, does David Cameron want to go down in history as the prime minister who rationed his compassion to a few hundred people when there was the opportunity to offer safety to so many more?"

Amnesty International UK director Kate Allen said: "The UK often prides itself on its history of offering sanctuary to refugees but this government can't hold its head high when it comes to the most vulnerable refugees from the conflict in Syria.

"Millions are living in extremely precarious conditions in neighbouring countries. Given the numbers, it is shocking that the UK has only taken in 90 refugees since it agreed to a resettlement programme a year ago.

"The international community must urgently step up its efforts to take the pressure off Syria's neighbours and resettle the most vulnerable of these refugees for whom protection here could literally be a matter of life or death."

Oxfam chief executive Mark Goldring said: "This is about Britain standing side by side with a region in crisis and offering to improve the lives of some of the most desperate Syrian refugees.

"Our aid contribution has been highly generous, but we can no longer continue to treat this problem solely at arms length. For some refugees, life in camps or makeshift shelters is not just hard, it is impossible.

"A year ago we promised to reach out to these most vulnerable people, but so far Britain has not done enough to live up to that promise."

This is a list of the celebrities who signed the letter to David Cameron: